Machine for slotting screw blank heads by means of a reciprocating cutting tool



Feb, 11, 1958 P. CHIAIA 2,822,556

MACHINE FOR SLOTTING SCREW BLANK HEADS BY MEANS OF A RECIPROCATING cummTOOL Filed July 20. 1953 FIG.2

INVENTOR ATTORNEY United States Patent I MACHINE roiisrlorrmo sgREwBLANK HEADS gg ignANs OF A RECIPROCAITING CUTTING Paolo Chiaia, Milan,Italy Application July 20, 1953, Serial 1%. 369,066

Claims priority, application Italy April 14, 1953 3 Claims. (Cl. 10-6)The present invention relates to a screw blank head slotter whichdiffers from conventional slotters in that it is provided with areciprocating cutting tool instead of a circular saw.

In conventional screw head slotters the slot is cut by lowering ontosaid head a rotating milling cutter. Such a system generally presentsthe following shortcomings:

(a) A high tool cost;

(b) A facility for the cutters to break;

(c) The necessity of effecting the cutting with a coolant, whichrequires a drying operation.

To avoid such shortcomings, the machine according to the invention ischaracterized by the fact that the slot is cut in the screw blank headby means of an unvariable profile cutter reciprocating two or more timeson the screw blank head, each time at a greater depth,-

vention is hereunder described by way of example with reference toFigures 1 and 2 of the annexed drawing, which show respectively apartially sectioned side elevation and a similar end elevation of thesame.

The screw blanks 1 in which the slot is to be cut, are introduced intothe intermittently rotating drum 2. By means of said drum 2 each blank 1is individually brought in front of the tool 3 in the position 4, whereit remains locked by a lever (not represented); all this being donethrough a known automatic mechanism which is, therefore, not described.

The tool 3 cuts the slot in the blank head 1 in the locked position 4accomplishing with a reciprocating motion two or more strokes in unisonwith the guide cylinder or carriage 5 along shaft 6. The reciprocatingmovement of the tool is generated by cam 7 acting upon lever 8 connectedby a double link 9 to carriage 5.

To increase at each passage the cutting depth of the tool 3, the latteris subjected at each passage to a greater pressure, obtained through thevarious steps of cam 10, operating push rod 11 and saddle 12 loaded by aspring 13 and push-rod 14 adjustably mounted on tool holder 15 fulcrumedat 16. Shaft 17 of cam is connected by means of a gear train 18, 19, 20and 21 to shaft 22 of cam 7 with such a ratio as to cause cam 7 torotate during one rotation of cam 10 a number of revolutionscorresponding to the number of steps of cam 10 plus one, that is, plusone turn corresponding to the time necessary for charging drum 2.Push-rod 14 is threaded in a boss 27 reciprocatable on a slide 25 bymeans of a screw 28 to vary the lever arm between fulcrum pin 16 and thetip of push rod 14, and the lever arm between the tip of push rod 14 andthe slide 12. Thus the effect of the cam 10 can be increased ordecreased to increase or decrease the feed of the tool 3 always with asame cam 10. V

As'the machine according to the invention is intended to be a universalone, that is, to take care of small 2,822,556 Pa en ed Fee, 5

and large screws; provision has been made to" vary' the number ofstrokes of thetool according to the size of the blank heads. j 5 V Tothis end; on shaft 1 7 aremoameq side by side severars'te'pp d cams 10,ofwh1ch only one-isinsight, each one of which presents a specialpr'ofile' to' impart to the tool' 3 a differentnuniberofs'troke's;,Tovary the num- 'ber of strokes it is sufliientto move over to thecorresaid ratio, lever 23 which is loose on shaft 22 and carries loosegear 21 is axially displaced and its spring pin 24 is selectivelyintroduced into a reference hole 25, thus automatically meshing loosegear 21 with one of gears 20.

The advantages of the screw blank head slotting machine provided with areciprocating cutter, can be recapitulated as follows:

(a) The obtention of an absolutely straight bottom cut; I

(b) A remarkable cutter economy, as instead of costly short livedmilling cutters, cheap plain easily made tools are used;

(c) The possibility of dry cutting, eliminating the subsequent tumblerdrying of the blanks;

(d) The ease of regrinding the tools without the help of automaticmachinery that is necessary for the milling cutters.

What I claim is:

1. A screw head slotter comprising a fixed-profile tool, means forfeeding blanks successively to and retaining them at a work station,first cam-actuated means for reciprocating the tool in a rectilinearmotion at and across the work station comprising a single-rise camhaving a progressive slope followed by an abrupt termination and a dwellportion, second cam-actuated means for feeding the tool progressivelytoward the blank a predetermined amount for each stroke applied to thatblank, and a gear train relating the movements of both cam-actuatedmeans in a fixed cycle; the second cam-actuated means comprising amultiple-rise cam and a shaft whereon the multiple-rise cam is mounted,a dwell portion on said multiple-rise cam for controlling the retractionof the tool to enable indexing of the blanks at the work station; thegear-train comprising a first gear also mounted on the shaft and a lastgear driving the first cam-actuated means, the gear ratio from first tolast gears being such that for each rotation of the multiple-rise camthe first cam-actuated means are driven a number of times equal to thenumber of rises of the multiple-rise cam plus one.

2. A screw head slotter comprising ,a fixed-profile tool, means forfeeding blanks successively to and retaining them at a work station,first cam-actuated means for reciprocating the tool in a rectilinearmotion at and across the work station comprising a single-rise camhaving a progressive slope followed by an abrupt termination and a dwellportion, second cam-actuated means for feeding the tool progressivelytoward the blank a predetermined amount for each stroke applied to thatblank, and a gear train relating the movements of both cam-actuatedmeans in a fixed cycle; the second cam-actuated means comprising a shaftand aplurality of multiple-rise cams respectively of different profilesmounted on the shaft, a dwell portion on each of said multiple-rise camsfor'controlling the retraction of the tool to enable indexing of theblanks at the work station; the gear train comprising a first gear alsomounted on the shaft, a last gear driving the first cam means, a set ofintermediate gears respectively of different diameters mounted on acommon counter-shaft and including a ment means operatively connected tothe oscillating cam for oscillation thereby, second abutment means onthe r 4 tool holder operatively connected to the oscillating slide foractuation thereby, and means for varying the relative positions of thetwo abutment means to vary the lever arms of the slide and pivoted toolholder.

References Cited in the file of this patent UNITED STATES PATENTS1,025,305 Rasmussen May 7, 1912 1,217,396 Boerner Feb. 27, 19171,829,215 Fox Oct. 27, 1931

